As a type of 3D porous bulk material, metal foams are of great practical importance in many engineering fields. Conventionally, metal foams have been widely used for heat exchangers, filters, energy and sound absorbers. Recently, open-cell metal foams have caught much attention for their new applications as charge collectors/mass support for the electro-active materials for lithium ion batteries (LIBs), super-capacitors, fuel cells, and sensors. Compared with porous nano-materials, open-cell metal foams stand out for their low cost, easy fabrication, good mechanical properties, high porosity, light weight, and high thermal and electrical conductivities. The decent-sized (e.g., several centimeters thick) and robust framework offered by open-cell metal foams are extremely attractive for simple and fast device integration and assembly.